Interpretive Summary: Flavonoids and hydroxycinnamates are phenolic compounds found throughout the plant kingdom that have purported health-promoting effects. These phenolic compounds were identified in 24 common beans representing 17 varieties commonly consumed by the U.S. public. Hydroxycinnamates were found in all of the beans, but the flavonoid content was distinctively different. The pattern of the flavonoid content of the beans allowed them to be organized into 6 different groups.

Technical Abstract:
Based on the phenolic profiles obtained by liquid chromatography/electrospray ionization mass spectrometry (LC-DAD-ESI/MS), 24 common bean samples representing 17 varieties and 7 generic off-the-shelf items belonging to ten dry bean commercial market classes can be organized into six different groups. All of the tested beans contained the same hydroxycinnaminic acid derivatives, but the glycosylated flavonoid components showed distinct differences. Black beans contained primarily the 3-O-glucosides of delphinidin, petunidin and malvidin, while pinto beans contained kaempferol and its 3-O-glycosides. Light red kidney beans contained trace amounts of quercetin 3-O-glucoside and its malonates, but pink and dark red kidney beans contained the diglycosides of quercetin and kaempferol. Small red beans (also known as red Mexican) contained mainly kaempferol 3-O-glucoside and pelargonidin 3-O-glucoside, while no detectable amounts of flavonoids were detected in alubia, cranberry, great northern, and navy beans. This is the first report of the isolation of quercetin 3-O-pentosylhexoside and flavonoid glucoside malonates, and the first detailed detection of hydroxycinnamates, in common beans.